Fastener for connecting and spacing parts

ABSTRACT

Fastener ( 1 ) comprising a head ( 2 ) and a body ( 3 ), the head ( 2 ) comprising a transverse stop ( 5 ) able to bear on the first piece ( 23 ), and the body ( 3 ) comprising a first spacer ( 10 ) and a second spacer ( 11 ), coaxial and disposed in line with each other in an axial direction, the first spacer ( 10 ), adjacent to the head ( 2 ), having a diameter greater than that of the second spacer ( 11 ) which extends starting from the first spacer ( 10 ), on the opposite side from the head ( 2 ), each of the spacers ( 10, 11 ) comprising at least one lug ( 13;18 ).

[0001] The invention relates to the field of the fastening andpositioning of mechanical parts.

[0002] It concerns more particularly a fastener comprising spacersadapted for the assembly of two parts each comprising a through-hole.

[0003] In numerous fields, in particular the automotive field, it isnecessary to have available fasteners capable of connecting two partstogether while ensuring the double function of relative fixing as wellas spacing.

[0004] Mechanical parts of all types, such as mechanical links, axles orrods thus need to be connected to the frame or structure of the systemto which they belong, while being held away from that frame orstructure.

[0005] Furthermore, such fasteners must be designed to promote rapidassembly, often performed blind, within mechanical structures withdifficult access.

[0006] Devices of the prior art are already capable of fulfilling thesefunctions. For example, a simple screw/nut system provided with aspacer, or a rivet tightened after spacing apart of the parts, or againcertain types of resin.

[0007] Although these known devices ensure the fixing and spacing of theparts, they have high mechanical complexity making them difficult toimplement on an automated production line. Their assembly requiresdifferent operations (the spacing apart and fixing being ensured bydifferent parts) and their withdrawal, when possible, is also complex.

[0008] The object of the invention is to provide a simple fastenerensuring the functions described above and being easy to mount, in orderto be suitable for automation and/or for implementation in conditionswhere access is difficult.

[0009] To that end the invention relates to a fastener comprising a headand a body, intended for connecting a first piece and a second piece,each comprising a through-hole with a predetermined contour, the firstand second pieces having respectively a first and second predeterminedthickness, characterized in that the head comprises a transverse stopable to bear on the first piece, and in that the body comprises a firstspacer and a second spacer, coaxial and disposed in line with each otherin an axial direction, the first spacer, adjacent to the head, having adiameter greater than that of the second spacer which extends startingfrom the first spacer, on the opposite side from the head, each of thespaces comprising at least one lug, the lugs on the first spacer beingseparated from the head by a distance corresponding substantially to thesaid first thickness and the lugs on the second spacer being separatedfrom the first spacer by a distance corresponding substantially to thesaid second thickness, the lugs on the first spacer being aligned withthe lugs on the second spacer.

[0010] Such a fastener is adapted to be easily mounted, in a singleoperation. The principle of lugs fixed on the spacers permits thelocking of the fastener onto the first part and onto the second part,simultaneously, by a simple rotation of the body.

[0011] The withdrawal of the fastener is not only possible but as simpleas the mounting of which the operations are repeated in the oppositeorder.

[0012] These operations are limited to the insertion of the fastenerthen to its rotation for example through a quarter turn.

[0013] According to one embodiment, the fastener is made in a singlepiece.

[0014] The structure of the fastener makes such one-piece manufacturepossible, for example by molding, which is simpler and thus the cost isadvantageous.

[0015] According to a preferred feature of the invention, the joinbetween the first spacer and the second spacer forms a shoulder defininga transverse abutment surface.

[0016] This transverse abutment surface plays the same role for thesecond part as the transverse stop bearing on the first part.

[0017] Each of the parts is thus held on one of its faces by a surfaceor a transverse stop, and on the other of its faces by the lugsrespectively arranged on the first and second spacers.

[0018] Additional functions may furthermore be provided in accordancewith the features of the fastener described.

[0019] Thus, the second spacer may comprise, at its join with the firstspacer, a frangible region of lesser thickness.

[0020] When forces in opposite directions are applied to the parts, withthe fastener in place, the shear or tension stress produced will resultin the rupture of that frangible region.

[0021] The force threshold to reach to cause the rupture is determinedby the dimensions of the frangible region and by the properties of thematerial used in manufacture.

[0022] Furthermore, for improved bearing on the first part, thetransverse stop on the head may be a projecting collar on the peripheryof the head.

[0023] Other preferred features of the invention relate to this collar.It may be elastically deformable in the axial direction so as to ensuretake-up of axial play.

[0024] Stable fastening is thus obtained, even after rotation of thefastener.

[0025] Similarly, the collar may comprise two cut-outs leaving anaxially movable locking tooth.

[0026] This locking tooth inserts into a cavity provided on the firstpart. This cavity is positioned such that the locking tooth comesopposite to it after rotation of the fastener.

[0027] The width of the said locking tooth may be substantially equal tothe width of the lugs of the first. This makes it possible to lock thetooth directly onto a part of the through hole of the first part.

[0028] According to another preferred feature of the invention, thesecond spacer comprises a chamfer at its end that is opposite from thehead.

[0029] This chamfer forms a frusto-conical portion on the end of thesecond spacer. As the fastener according to the invention is adapted tobe inserted in two coaxial holes, this frusto-conical portionfacilitates the entry of the fastener into its housing.

[0030] Similarly the lugs of the second spacer may comprise beveledportions adapted to facilitate the entry of the fastener into itshousing or adapted to facilitate the operation of locking by rotation ofthe fastener.

[0031] Other features and advantages of the invention appear in thelight of the following description of a preferred embodiment, given byway of non-limiting example, and made with reference to the accompanyingdrawings in which:

[0032]FIG. 1 is a perspective view of a fastener according to thepresent invention;

[0033]FIG. 2 is a front view of the fastener of FIG. 1;

[0034]FIG. 3 is a side view of the fastener of FIG. 1;

[0035]FIG. 4 is a top view of the fastener of FIG. 1;

[0036]FIG. 5 is a front view of an assembly of parts adapted to beassembled by the fastener of FIG. 1, this Figure showing the profile ofthe perforations adapted to cooperate with the fastener.

[0037]FIG. 6 is a side view on VI-VI of the assembly of parts of FIG. 5,solely the two perforated parts being adapted to be assembled by thefastener of FIG. 1;

[0038]FIG. 7 is a top view in section on VII-VII of the assembly ofparts of FIG. 5, two of those parts being assembled by the fastener ofFIG. 1;

[0039]FIG. 8 is a section view of the assembly of FIG. 7, with the samesection as in FIG. 6.

[0040] The fastener 1 appearing in isolation in FIGS. 1 to 4 comprises ahead 2 and body 3 as its main parts.

[0041] The head 2 is adapted for the manipulation of the fastener 1 andcomprises a transverse disc 4 of which the periphery is provided with aprojecting collar 5.

[0042] Means for manipulation are also provided on the head 2, herecomprising a tongue 6 for gripping, since the fastener 1 is adapted inthe present embodiment, for being manipulated by hand.

[0043] With reference to FIG. 3, the tongue 6 for this purpose has facesthat converge towards each other so as to be able to be graspedoptimally between the thumb and index finger of the user.

[0044] The collar 5 is formed by a frusto-conical wall delimiting acircle of smaller diameter and a circle of larger diameter, the circleof smaller diameter being attached to the edge of the transverse disc 4and the circle of larger diameter being positioned around the body 3.

[0045] As can be seen in FIGS. 2 and 3, the collar 5 thus forms afrusto-conical surface flaring from the disc 4 towards the body 3.

[0046] The collar 5 is moreover constituted by an elastic materialenabling it to be deformed when a force is applied to it tending tobring the circle of larger diameter into the plane of the transversedisc 4.

[0047]FIGS. 1 and 4 show furthermore that the collar 5 comprises twocut-outs 7 delimiting a locking tooth 8.

[0048] The locking tooth 8 is thus movable in the axial direction, thatis to say in the general direction in which the fastener 1 extends,independently of the rest of the collar 5.

[0049] Tooth 8 further comprises a projection 9 (FIG. 3), in thedirection of the body, adapted to ensure the locking of the fastener inthe manner set out hereinafter.

[0050] The body 3 of the fastener 1 comprises a first spacer 10 attachedto the head 2 so as to be coaxial with the transverse disc 4 of the head2. A second spacer 11 is also provided on the body 3, this spacer 11being coaxially attached to the first spacer 10 on the opposite sidefrom the head 2.

[0051] The transverse disc 4 of the head 2, the first spacer 10 and thesecond spacer 11 are all three coaxially disposed, their common axisdefining the general direction in which the fastener 1 extends.

[0052] The first spacer 10 has the form of a cylinder which comprisesrecesses 12 as well as two lugs 13 projecting from the contour of thecylinder.

[0053] The recesses 12 are formed, according to the present embodiment,in the first spacer 10 for reasons of economy of material on molding aswell as for improvement in the weight of the finished part.

[0054] Other recesses may be provided in the same manner provided thatthe initial cylinder keeps a circular section.

[0055] The lugs 13 project from the contours of the cylinder in asubstantially parallelepiped form. Nevertheless, the faces of the lug 13that are remote from the cylinder are rounded such that the lugs 13 arecontained within the collar 5 of the head 2 when the fastener 1 isviewed from below (FIG. 4).

[0056] With reference to FIG. 2, the height of the lugs 13 substantiallycorresponds to two-thirds of the height of the spacer 10 to which theycorrespond and are disposed flush with the end that is on the oppositeside from the head 2 of the first spacer 10. A space 14 is provided inthis manner between the lugs 13 and the head 2 (the space here having aheight of approximately one-third of the height of the first spacer 10)or more specifically between the lugs 13 and the collar 5 of the head 2.

[0057] The height of the space 14 is dimensioned depending on thethickness of one of the parts to assemble as set out later.

[0058] The second spacer 11 is formed from a solid cylinder neverthelesscomprising a chamfer 15 at its end that is opposite from the head 2.

[0059] The diameter of this cylinder is less than the diameter of thecylinder forming the first spacer 10 so as to create a shoulder, that isto say that when the fastener 1 is viewed from the side (FIGS. 2 and 3),the first spacer 10 has a transverse abutment surface 16 extendingbeyond the projection of the contour of the second spacer 11 on the endthat is opposite from the head 2 of the first spacer 10.

[0060] This abutment surface 16 may thus bear on a part when the secondspacer has been inserted in an aperture made in said part (the diameterof this aperture being greater than that of the second spacer 11 butless than that of the first spacer 10).

[0061] The second spacer 11 is attached to the first spacer 10 by acylindrical region 17 having a diameter less than that of the cylinderforming the second spacer 11.

[0062] This region of lesser thickness 17 is destined to form afrangible region adapted to break above a predetermined shear force, itbeing possible for the shear force to be created by a relativedisplacement of the two fastened parts, when fastener 1 is in place.

[0063] To hold fastener 1 in place on those two fastened parts, thesecond spacer 11 is provided with two diametrically opposed lugs 18projecting transversely of the spacer 11, at its end that is on theopposite side from the first spacer 10.

[0064] The lugs 18 are thus attached to the second spacer 11 adjacentthe chamfer 15.

[0065] As for the first spacer 10, a space is thus provided between thelugs 18 of the second spacer 11 and the lugs 13 of the first spacer 10,this space corresponding to the thickness of one of the parts toassemble.

[0066] The lugs 18 of the second spacer 11, of which one is visible fromthe side in FIG. 3, each comprise an upper surface 19 and a lowersurface 20, as well as beveled side walls 21.

[0067] The characterization of these surfaces as upper, lower and sideis made with reference to the fastener 1 in the position of FIG. 3.

[0068] Moreover, considering FIG. 2 again, the lugs 18 of the secondspacer 11 also comprise a bevel 22 on their end wall, that which is onthe opposite side from the spacer 11.

[0069] The fastener 1 which has just been described may be utilized inthe manner indicated below.

[0070] The fastener 1 is adapted to rigidly assemble a first part 23 anda second part 24, while maintaining a space between the two of them, inaccordance with the assembly of FIG. 7. The presence of a third part 25close to the second part 24 does not participate in said assembly but,in FIGS. 6 to 8, makes it possible to simulate an environment in whichthe second part 24 is not accessible and in which that second part 24 isdisposed virtually against another member (here the third part 25),leaving little space for the lugs 18 of the second spacer 11.

[0071] With reference to FIG. 5, the two parts 23, 24 to be assembledeach comprise a perforation 26, 27 passing all the way through havingthe form of a circular hole associated with two diametrically opposedrectangular holes biting into the periphery of the circular hole.

[0072] This configuration of the perforations 26, 27 makes it possibleit possible to introduce into each of them a spacer provided with lugsand to lock it by a quarter turn as explained further on.

[0073] The two perforations 26, 27 have identical shape but are ofdifferent size: perforation 26 of the first part 23 is larger thanperforation 27 of the second part 24. The diameter of the circular holeof perforation 26 of the first part 23 corresponds to the diameter ofthe first spacer 10 of the fastener 1, and the width of the rectangulardiametrically opposed holes corresponds to the width of the lugs 13 ofthe first spacer 10.

[0074] Similarly, the diameter of the circular hole of perforation 27 ofthe second part 24 corresponds to the diameter of the second spacer 11of the fastener 1 and the width of the rectangular diametrically opposedholes corresponds to the width of the lugs 18 of the second spacer 11.

[0075] Finally, the thickness of the first part 23 corresponds to thedistance 14 separating the first spacer 10 from the head 2 and thethickness of the second part 24 corresponds to the distance between thefirst spacer (more specifically: the abutment surface 16) and the uppersurface 19 of the lugs 18 of the second spacer 11. Since parts 23, 24have perforations 26, 27 satisfying these conditions, it is possible toassemble and space them with the fastener 1.

[0076] The two parts 23, 24 are first of all put into position inaccordance with FIGS. 5 and 6, that is to say such that the perforations26, 27 are coaxial and such that the two pairs of rectangular holes arein line with each other.

[0077] Fastener 1 is then inserted through the two perforations 26, 27,the lugs 13, 18 being positioned face-to-face with the rectangular holesof the perforations 26, 27.

[0078] Note that the chamfer 15 and the bevels 21, 22 of lugs 18 of thefirst spacer 11 are adapted to facilitate the insertion of the fastener1.

[0079] This insertion is made with one hand, holding the tongue 6between the thumb and the index finger, and may consequently beperformed blind.

[0080] Once the fastener 1 has been fully inserted through both parts23, 24, the user must still exert a force to press the head 1 againstthe first part 23, elastically deforming the collar 5, andsimultaneously rotate the fastener 1 by a quarter turn.

[0081] The bevels 21 of the lugs 18 of the second spacer 11 serve hereto facilitate the start of this rotation, for example alleviating thefact that the fastener 1 may be insufficiently pressed against the firstpart 23, this pressing being necessary in order for the lugs 13, 18 tobe freed from the rectangular holes of the two perforations 26, 27.

[0082] Once the quarter locking turn has been made, the fastener 1 is inplace on the two parts 23, 24 as represented in FIGS. 7 and 8.

[0083]FIG. 7 shows the holding of the first part 23 between the lugs 13,18 and the holding of the second part between the collar 5 and the lugs13 of the first spacer 10. The elasticity of the collar 5 is takenadvantage of to take up the plays of the assembly or to compensate forcreep of the fastener 1.

[0084]FIG. 8 shows the locking tooth 8 of which the projection 9 becomesinserted in a cavity 28 arriving opposite that tooth 8 after the quarterlocking turn has been made. This cavity 28 may be a cavity speciallycreated for that purpose or else, as is the case here, cavity 28 may beone of the rectangular holes of the perforation 26 of the first part 23.

[0085] The third part 25, or any other member preventing access to oneof the sides of the assembly, in no way interferes with the mountingoperation described due to the insertion of the fastener from a singleside and due to the fineness of the lugs 18 of the second spacer.

[0086] The frangible region 17 is thus positioned within the thicknessof the second part 24 (see FIGS. 7 and 8), flush with that part on theside of the abutment surface 16 of the first spacer 10.

[0087] In this position, the rupture of this frangible region 17 leadsto the separation of parts 23, 24 but the maintenance of their spacingsince the part of the fastener 1 formed of the head 2 and the firstspacer 10 remains in place on the first part 23.

[0088] The force necessary for the rupture of the frangible region 17,in shear or in tension, may be calibrated to correspond to a stresslimit induced by a relative movement between the two parts 23, 24. Thisis the case when such an assembly is adapted to remain integral underthat stress limit and, on the contrary, be broken above it.

[0089] Depending on the desired value of this stress limit and on thematerial used to form the fastener 1, the frangible region 17 may bedimensioned by calculation and/or empirically, through rupture tests.

1. Fastener (1) comprising a head (2) and a body (3), intended forconnecting a first piece (23) and a second piece (24), each comprising athrough-hole (26; 27) with a predetermined contour, the first (23) andsecond (24) pieces having respectively a first and second predeterminedthickness, characterized in that the head (2) comprises a transversestop (5) able to bear on the first piece (23), and in that the body (3)comprises a first spacer (10) and a second spacer (11), coaxial anddisposed in line with each other in an axial direction, the first spacer(10), adjacent to the head (2), having a diameter greater than that ofthe second spacer (11) which extends starting from the first spacer(10), on the opposite side from the head (2), each of the spacers (10,11) comprising at least one lug (13;18), the lugs (13) on the firstspacer (10) being separated from the head (2) by a distancecorresponding substantially to the said first thickness and the lugs(18) on the second spacer (11) being separated from the first spacer(10) by a distance corresponding substantially to the said secondthickness, the lugs (13) on the first spacer (10) being aligned with thelugs (18) on the second spacer (11).
 2. Fastener according to claim 1,characterized in that it is made in a single piece.
 3. Fasteneraccording to claim 1 or 2, characterized in that the join between thefirst spacer (10) and the second spacer (11) forms a shoulder defining atransverse abutment surface (16).
 4. Fastener according to one of claims1 to 3, characterized in that the second spacer (11) comprises, at itsjoin with the first spacer (10), a frangible region (17) of lesserthickness.
 5. Fastener according to one of claims 1 to 4, characterizedin that the transverse stop on the head is a projecting collar (5) onthe periphery of the head (2).
 6. Fastener according to claim 5,characterized in that the collar (5) is elastically deformable in theaxial direction so as to provide a taking up of axial play.
 7. Fasteneraccording to claim 5 or 6, characterized in that the collar (5)comprises two cut-outs (7) leaving an axially movable locking tooth (8).8. Fastener according to claim 7, characterized in that the width of thesaid locking tooth (8) is substantially equal to the width of the lugs(13) of the first spacer (10).
 9. Fastener according to claim 1 to 8,characterized in that the second spacer (11) comprises a chamfer (15) atits end that is opposite from the head (2)
 10. Fastener according to oneof claims 1 to 9, characterized in that the lugs (18) on the secondspacer (11) comprise beveled portions (21, 22).
 11. Fastener accordingto one of claims 1 to 10, characterized in that the head (2) comprises atongue (6) for manual gripping and in that the first spacer (10) and thesecond spacer (11) each comprise two diametrically opposed lugs (13;18),the lugs (13) on the first spacer (10) being aligned with the lugs (18)on the second spacer (11).